Thursday, July 5, 2012By Dan Elliott ,AP

DENVER -- Five Air Force tanker planes were cleared Tuesday to return to firefighting after a deadly weekend crash, bringing much-needed help in the battle against the worst U.S. wildfires in decades.

The decision to suspend the Air Force's C-130 flights had left just 14 federally contracted heavy tankers in use during one of the most destructive wildfire seasons ever to hit the West.

Sunday's crash in the Black Hills of South Dakota killed four crewmembers and injured the other two. The cause was still under investigation.

As of Tuesday afternoon, none of the five grounded tankers had yet been sent on any missions.

The National Interagency Fire Center, which coordinates wildfire-fighting efforts nationwide, said 45 large fires were burning Tuesday, including 36 in nine Western states.

In Colorado alone, three fires have destroyed more than 600 homes and killed six residents.

The C-130 planes can be called into firefighting duty if all the civilian heavy tankers are in use or unavailable. The planes can drop 3,000 gallons (11,300 liters) of water or fire retardant within seconds.

Sunday's crash was the first for an Air Force C-130 on firefighting duty since the program started in the 1970s, said Jennifer Jones, a spokeswoman for national fire center.

A privately owned civilian version of an older C-130 crashed in California in 2002, killing three crewmembers. The crash helped prompt a review of large U.S. air tankers and led ultimately to a greatly reduced fleet of civilian planes.

Secretary of Agriculture Tom Vilsack, whose department includes the U.S. Forest Service, said heavy tankers are only part of the firefighting air force.

“It's not just about tankers. It's about helicopters, fixed-wing aircraft, a combination of assets,” Vilsack said during a visit to the Idaho fire center Tuesday.